Flavonoid profile of Anoectochilus roxburghii (Wall.) Lindl. Under short-term heat stress revealed by integrated metabolome, transcriptome, and biochemical analyses

OpiCa1 reduces inflammation and ROS levels counteracting heat stress-induced cardiac injury

Heat stress exacerbates heart disease by increasing myocardial workload, and long-term exposure to high temperatures elevates cardiovascular risks. As a natural cell-penetrating peptide, OpiCa1 can rapidly bind to ryanodine receptors (RyRs), inducing a semi-open conformation and triggering calcium release. We explored OpiCa1's protective role against heat stress at 42 °C using cell viability assays, transcriptomics, and whole animal studies. Experiments showed that OpiCa1 treatment in heat-stressed H9C2 cells significantly reduced ROS, apoptosis, and inflammatory factors while increasing cell survival. OpiCa1 binds to RyRs, inducing a subconductive state and consequently restoring mitochondrial calcium homeostasis. It inhibits FOS-mediated apoptosis via modulation of the Bax/Bcl-2 ratio and suppresses inflammatory responses by regulating MAPK and PI3K signaling pathways. In heat-stressed mice, OpiCa1 significantly mitigated cardiac injury, reduced the expression levels of IL-1α and IL-6, and improved tissue integrity. Our findings reveal OpiCa1's dual function in mitigating oxidative stress and inflammation via critical apoptotic and signaling pathways, thereby presenting a promising therapeutic approach for heat-related cardiovascular disorders.

Identification and Functional Characterization of Two UDP-Glycosyltransferases Involved in Narcissoside Biosynthesis in Anoectochilus roxburghii

Flavonoid rutinosides, a group of bioactive compounds in Anoectochilus roxburghii, contribute greatly to the plant's beneficial effects on human health. However, the glycosylation mechanism of flavonoid rutinosides in A. roxburghii remains unclear. In this study, two efficient and selective glycosyltransferases, AUTG25 and AUTG23, involved in the biosynthesis of narcissoside, a major flavonoid rutinoside in A. roxburghii, were identified through transcriptome analysis and functional validation. AUTG25 could regioselectively catalyze 3-O-glucosylation of isorhamnetin to produce isorhamnetin 3-O-glucoside, while AUTG23 could further catalyze 6"-O-rhamnosylation to generate narcissoside. Both AUTG25 and AUTG23 exhibited high positional and sugar donor selectivities in the catalytic reaction. Homology modeling and site-directed mutagenesis showed that H20, E83, E385, and F143 in AUTG25 and E280, E89, D188, W327, D369, and Y191 in AUTG23 may be critical for their catalytic functions. Transient expression in Nicotiana benthamiana finally confirmed that AUTG25 possesses flavonol-3-O-glucosyltransferase activity and AUTG23 has flavonol-3-O-glucoside (1→6) rhamnosyltransferase activity. This study clarified and provided candidate UDP-dependent glycosyltransferase genes for narcissoside biosynthesis in A. roxburghii.

DIA-based quantitative proteomics explores the mechanism of amelioration of APAP-induced liver injury by anoectochilus roxburghii (Wall.) Lindl

Background

Drug-induced liver injury (DILI) is the most common cause of acute liver injury. Anoectochilus roxburghii (Wall.) Lindl. (AR) and its polysaccharide fractions (ARPs) have been shown to have effective therapeutic effects with minimal side effects on a wide range of diseases including hepatopathy. This study aims to determine the therapeutic effects of ARPs on acetaminophen (APAP)-induced liver injury and to explore the mechanistic pathways involved.

Methods

C57BL/6J male mice at 8 weeks were used to construct a model of APAP-induced liver injury. The acute hepatic injury was induced by oral administration of APAP (300 mg/kg) before 16 h fasting. For therapeutic experiment, mice were gavaged with the water extract of AR (AR.WE) or the purified ARPs before and after APAP administration. Biochemical analyses, ELISA analyses, H&E staining, RT-PCR, and Quantitative proteomic analysis were used to investigate the effects and mechanisms of AR on DILI.

Results

Both AR.WE. and the purified ARPs treatment reduced APAP-induced liver injury, decreased hepatic glutathione and TNF-α levels, alleviated oxidative stress and inflammation. Quantitative proteomic analysis revealed that ARPs downregulated the protein levels involved in apoptosis, inflammation, oxidative stress, necroptosis, while upregulated the protein levels involved in autophagy. These protective effects of ARPs are possibly related to the downregulation of vATPase activity and thus participating in the autophagic process and ferroptosis.

Conclusion

ARPs can protect mice against APAP-induced liver injury, alleviate oxidative stress and inflammation. Our study reveals a potential therapeutic effect for ARPs in protecting APAP-induced liver injury.

Effects of Different Postharvest Treatments on Fruit Quality, Sucrose Metabolism, and Antioxidant Capacity of 'Newhall' Navel Oranges During Storage

During the post-harvest storage of citrus, the flavor of fruit gradually fade. In this study, we investigated the effects of different treatments-control check (CK), heat treatment (HT), salicylic acid treatment (SA), and 1-methylcyclopropene treatment (1-MCP)-on the quality of 'Newhall' navel oranges, particularly focusing on sucrose metabolism and related gene expression during storage. Combining the experimental data, we compared the three different treatments with CK. The results showed that the oranges subjected to HT had a significantly higher flavonoid content (26.40 μg) and total phenolic content (19.42 μg) than those used for the CK at the late storage stage, and was also the most effective in slowing the decline in sugar, titratable acid and other indexes, followed by SA, with 1-MCP performing poorly. Quantitative results showed that the three treatments contributed to the increase in sucrose content by elevating the expression of the SPS1 and SPS2 genes involved in sucrose synthesis compared to the CK. However, no clear pattern was observed between the genes involved in sucrose catabolism (SUS1 and SUS3) and sucrose content. These results provided a rationale for the selection of post-harvest treatments to extend the storage life and maintain the quality of 'Newhall' navel oranges, with broader implications for the citrus industry.

Transcriptomic and Metabolomic Insights into Key Genes Involved in Kinsenoside Biosynthesis in Anoectochilus roxburghii

As the main active ingredient in Anoectochilus roxburghii, kinsenoside has important health and medical effects including hepatoprotective, anti-oxidant, and bacteriostasis, among others. In recent years, with the limited application of high-throughput technology to A. roxburghii, there has been no research on the key regulatory genes involved in the synthesis of kinsenoside. Therefore, we examined three species of A. roxburghii that are widely planted in mainland China and Taiwan Province, A. roxburghii cultivar 'Jian ye', Anoectochilus formosanus, and Anoectochilus burmannicus, determining the content of kinsenoside, performing transcriptomic and metabolomic sequencing, identifying UDP glycosyltransferases, and screening for UDP glycosyltransferases that may be involved in kinsenoside synthesis. The results showed that among the three species of A. roxburghii, the content of kinsenoside in A. roxburghii cv. 'Jian ye' was the highest. Transcriptome and metabolome data showed that A. roxburghii cv. 'Jian ye' and the two other species of A. roxburghii have 3702 and 5369 differentially expressed genes and 69 and 120 differentially accumulated metabolites, respectively. Meanwhile, differentially expressed genes and differentially accumulated metabolites are enriched in the glucose metabolism and hormone pathways. We also treated the A. roxburghii samples with exogenous auxin and characterized the related genes. In A. roxburghii, we identified 73 members of the UDP glycosyltransferase family. Through phylogenetic tree, transcriptome data expression profile, and qPCR analyses, we screened for members that may be involved in the synthesis of kinsenoside. In summary, the results of this study provide insights for breeding high-kinsenoside-content and high-intron varieties of A. roxburghii.

Integrated analysis of miRNA-mRNA regulatory networks in Anoectochilus roxburghii in response to blue laser light

Anoectochilus roxburghii (Wall.) Lind. has significant medicinal and economic value, and the social demand for this species is increasing annually. Laser light sources have different luminescent mechanisms compared with ordinary light sources and are also important factors regulating the synthesis of functional metabolites in A. roxburghii. However, the regulatory mechanism through which A. roxburghii responds to blue laser light has not been investigated. Previous studies have shown that blue-laser treatment results in more red leaves than blue- or white-light treatment. Here, the differences in the effects of laser treatment on A. roxburghii were analyzed by transcriptome sequencing. Gene Ontology analysis revealed that the membranes, calcium ion binding, brassinosteroid-mediated signaling pathway and response to salicylic acid play important roles in the response of A. roxburghii to blue laser light. Kyoto Encyclopedia of Genes and Genomes analysis revealed the involvement of multiple pathways in the response to blue-laser treatment, and among these, beta biosynthesis, flavone and flavonol biosynthesis, thiamine metabolism, limonene and pinene biosynthesis, and peroxisomes play core roles. Cytoscape interaction analysis of the differentially expressed miRNA targets indicated that novel_miR_66, novel_miR_78 and novel_miR_212 were most likely involved in the effect of blue laser light on A. roxburghii. Metabolic content measurements showed that blue laser light increased the beet red pigment, thiamine, total flavonoid and limonene contents, and qPCR analysis confirmed that novel_miR_21, novel_miR_66, novel_miR_188 and novel_miR_194 might participate in the blue-laser signaling network through their target genes and thereby regulate the functional metabolite accumulation in A. roxburghii. This study provides a scientific basis for high-yield A. roxburghii production.

De Novo Transcriptome Assembly of Anoectochilus roxburghii for Morphological Diversity Assessment and Potential Marker Development

Anoectochilus roxburghii is a rare and precious medicinal and ornamental plant of Orchidaceae. Abundant morphological characteristics have been observed among cultivated accessions. Our understanding of the genetic basis of morphological diversity is limited due to a lack of sequence data and candidate genes. In this study, a high-quality de novo transcriptome assembly of A.roxburghii was generated. A total of 138,385 unigenes were obtained, and a BUSCO (Benchmarking Universal Single-Copy Orthologs) analysis showed an assembly completeness of 98.8%. Multiple databases were used to obtain a comprehensive annotation, and the unigenes were functionally categorized using the GO (Gene Ontology), KOG (Eukaryotic Orthologous Groups), KEGG (Kyoto Encyclopedia of Genes and Genomes), and Nr databases. After comparing the phenotypic characteristics of five representative cultivars, a set of cultivar-specific, highly expressed unigenes was identified based on a comparative transcriptome analysis. Then, a WGCNA (Weighted Gene Co-expression Network Analysis) was performed to generate gene regulatory modules related to chlorophyll content (red) and sucrose synthase activity (black). In addition, the expression of six and four GO enrichment genes in the red and black modules, respectively, was analyzed using qRT-PCR to determine their putative functional roles in the leaves of the five cultivars. Finally, in silico SSR (Simple Sequence Repeat) mining of the assembled transcriptome identified 44,045 SSRs. Mononucleotide was the most dominant class of SSRs, followed by complex SSRs. In summary, this study reports on the phenomic and genomic resources of A. roxburghii, combining SSR marker development and validation. This report aids in morphological diversity assessments of Anoectochilus roxburghii.

Comparative Analysis of Citrus Species' Flavonoid Metabolism, Gene Expression Profiling, and Their Antioxidant Capacity under Drought Stress

Citrus species are widely cultivated across the globe and frequently encounter drought stress during their growth and development phases. Previous research has indicated that citrus species synthesize flavonoids as a response mechanism to drought stress. This study aimed to comprehensively quantify and analyze the presence of 85 distinct flavonoids in the leaf and root tissues of lemon (drought susceptible) and sour orange (drought tolerant). In drought-stressed sour orange roots, flavonoids, such as isosakuranin, mangiferin, trilobatin, liquiritigenin, avicularin, silibinin, and glabridin, were more elevated than control sour orange roots and drought-stressed lemon roots. Additionally, hydroxysafflor yellow A, cynaroside, tiliroside, and apigenin 7-glucoside were increased in drought-stressed sour orange leaves compared to drought-stressed lemon leaves. Under drought stress, flavonoids such as (-)-epigallocatechin, silibinin, benzylideneacetophenone, trilobatin, isorhamnetin, 3,7,4'-trihydroxyflavone, and liquiritigenin were significantly increased, by 3.01-, 3.01-, 2.59-, 2.43-, 2.07-, 2.05-, and 2.01-fold, in sour orange roots compared to control sour orange roots. Moreover, the total flavonoid content and antioxidant capacity were significantly increased in drought-stressed sour orange leaves and root tissues compared to drought-stressed lemon leaves and root tissues. The expression levels of genes involved in flavonoid biosynthesis were highly expressed in sour orange leaves and roots, compared to lemon leaves and root tissues, post-drought stress. These findings indicate that lemons fail to synthesize protective flavonoids under drought conditions, whereas sour orange leaves and root tissues enhance flavonoid synthesis, with higher antioxidant activities to mitigate the adverse effects of reactive oxygen species generated during drought stress.

Transcriptomics and metabolomics analyses of Rosa hybrida to identify heat stress response genes and metabolite pathways

BACKGROUND

Global warming has greatly increased the impact of high temperatures on crops, resulting in reduced yields and increased mortality. This phenomenon is of significant importance to the rose flower industry because high-temperature stress leads to bud dormancy or even death, reducing ornamental value and incurring economic losses. Understanding the molecular mechanisms underlying the response and resistance of roses to high-temperature stress can serve as an important reference for cultivating high-temperature-stress-resistant roses.

RESULTS

To evaluate the impact of high temperatures on rose plants, we measured physiological indices in rose leaves following heat stress. Protein and chlorophyll contents were significantly decreased, whereas proline and malondialdehyde (MDA) contents, and peroxidase (POD) activity were increased. Subsequently, transcriptomics and metabolomics analyses identified 4,652 common differentially expressed genes (DEGs) and 57 common differentially abundant metabolites (DAMs) in rose plants from four groups. Enrichment analysis showed that DEGs and DAMs were primarily involved in the mitogen-activated protein kinases (MAPK) signaling pathway, plant hormone signal transduction, alpha-linolenic acid metabolism, phenylpropanoid biosynthesis, and flavonoid biosynthesis. The combined analysis of the DEGs and DAMs revealed that flavonoid biosynthesis pathway-related genes, such as chalcone isomerase (CHI), shikimate O-hydroxycinnamoyl transferase (HCT), flavonol synthase (FLS), and bifunctional dihydroflavonol 4-reductase/flavanone 4-reductase (DFR), were downregulated after heat stress. Moreover, in the MAPK signaling pathway, the expression of genes related to jasmonic acid exhibited a decrease, but ethylene receptor (ETR/ERS), P-type Cu + transporter (RAN1), ethylene-insensitive protein 2/3 (EIN2), ethylene-responsive transcription factor 1 (ERF1), and basic endochitinase B (ChiB), which are associated with the ethylene pathway, were mostly upregulated. Furthermore, heterologous overexpression of the heat stress-responsive gene RcHSP70 increased resistance to heat stress in Arabidopsis thaliana.

CONCLUSION

The results of this study indicated that the flavonoid biosynthesis pathway, MAPK signaling pathway, and plant hormones may be involved in high-temperature resistance in roses. Constitutive expression of RcHSP70 may contribute to increasing high-temperature tolerance. This study provides new insights into the genes and metabolites induced in roses in response to high temperature, and the results provide a reference for analyzing the molecular mechanisms underlying resistance to heat stress in roses.

Multi-omics analysis reveals key regulatory defense pathways and genes involved in salt tolerance of rose plants

Salinity stress causes serious damage to crops worldwide, limiting plant production. However, the metabolic and molecular mechanisms underlying the response to salt stress in rose (Rosa spp.) remain poorly studied. We therefore performed a multi-omics investigation of Rosa hybrida cv. Jardin de Granville (JDG) and Rosa damascena Mill. (DMS) under salt stress to determine the mechanisms underlying rose adaptability to salinity stress. Salt treatment of both JDG and DMS led to the buildup of reactive oxygen species (H2O2). Palisade tissue was more severely damaged in DMS than in JDG, while the relative electrolyte permeability was lower and the soluble protein content was higher in JDG than in DMS. Metabolome profiling revealed significant alterations in phenolic acid, lipids, and flavonoid metabolite levels in JDG and DMS under salt stress. Proteome analysis identified enrichment of flavone and flavonol pathways in JDG under salt stress. RNA sequencing showed that salt stress influenced primary metabolism in DMS, whereas it substantially affected secondary metabolism in JDG. Integrating these datasets revealed that the phenylpropane pathway, especially the flavonoid pathway, is strongly enhanced in rose under salt stress. Consistent with this, weighted gene coexpression network analysis (WGCNA) identified the key regulatory gene chalcone synthase 1 (CHS1), which is important in the phenylpropane pathway. Moreover, luciferase assays indicated that the bHLH74 transcription factor binds to the CHS1 promoter to block its transcription. These results clarify the role of the phenylpropane pathway, especially flavonoid and flavonol metabolism, in the response to salt stress in rose.

Untargeted metabolomics in Anectocillus roxburghii with habitat heterogeneity and the key abiotic factors affecting its active ingredients

Introduction

Anoectochilus roxburghii is a rare, endangered herb with diverse pharmacological properties. Understanding the main metabolite types and characteristics of wild A. roxburghii is important for efficiently utilizing resources and examining quality according to origin.

Methods

Samples were collected from the main production areas across five regions in Fujian Province, China. An untargeted metabolomics analysis was performed on the entire plants to explore their metabolic profiles. We utilized UPLC-MS/MS to specifically quantify eight targeted flavonoids in these samples. Subsequently, correlation analysis was conducted to investigate the relationships between the flavonoids content and both the biological characteristics and geographical features.

Results

A comprehensive analysis identified a total of 3,170 differential metabolites, with terpenoids and flavonoids being the most prevalent classes. A region-specific metabolite analysis revealed that the Yongchun (YC) region showed the highest diversity of unique metabolites, including tangeretin and oleanolic acid. Conversely, the Youxi (YX) region was found to have the smallest number of unique metabolites, with only one distinct compound identified. Further investigation through KEGG pathway enrichment analysis highlighted a significant enrichment in pathways related to flavonoid biosynthesis. Further examination of the flavonoid category showed that flavonols were the most differentially abundant. We quantified eight specific flavonoids, finding that, on average, the YX region exhibited higher levels of these compounds. Correlation analysis highlighted a significant association between flavonoids and habitat, especially temperature and humidity.

Discussion

Untargeted metabolomics via LC-MS was suitable for identifying region-specific metabolites and their influence via habitat heterogeneity. The results of this study serve as a new theoretical reference for unique markers exclusively present in a specific sample group.

Multiomics Analyses Reveal the Dual Role of Flavonoids in Pigmentation and Abiotic Stress Tolerance of Soybean Seeds

The color of the seed coat has great diversity and is regarded as a biomarker of metabolic variations. Here we isolated a soybean variant (BLK) from a population of recombinant inbred lines with a black seed coat, while its sibling plants have yellow seed coats (YL). The BLK and YL plants showed no obvious differences in vegetative growth and seed weight. However, the BLK seeds had higher anthocyanins and flavonoids level and showed tolerance to various abiotic stresses including herbicide, oxidation, salt, and alkalinity during germination. Integrated metabolomic and transcriptomic analyses revealed that the upregulation of biosynthetic genes probably contributed to the overaccumulation of flavonoids in BLK seeds. The transient expression of those biosynthetic genes in soybean root hairs increased the levels of total flavonoids or anthocyanins. Our study revealed the molecular basis of flavonoid accumulation in soybean seeds, leveraging genetic engineering for both nutritious and stress-tolerant soybean germplasm.

Integrated Transcriptomics and Metabolomics Analysis of Two Maize Hybrids (ZD309 and XY335) under Heat Stress at the Flowering Stage

High temperature around flowering has a serious impact on the growth and development of maize. However, few maize genes related to flowering under heat stress have been confirmed, and the regulatory mechanism is unclear. To reveal the molecular mechanism of heat tolerance in maize, two maize hybrids, ZD309 and XY335, with different heat resistance, were selected to perform transcriptome and metabolomics analysis at the flowering stage under heat stress. In ZD309, 314 up-regulated and 463 down-regulated differentially expressed genes (DEGs) were detected, while 168 up-regulated and 119 down-regulated DEGs were identified in XY335. By comparing the differential gene expression patterns of ZD309 and XY335, we found the "frontloaded" genes which were less up-regulated in heat-tolerant maize during high temperature stress. They included heat tolerance genes, which may react faster at the protein level to provide resilience to instantaneous heat stress. A total of 1062 metabolites were identified via metabolomics analysis. Lipids, saccharides, and flavonoids were found to be differentially expressed under heat stress, indicating these metabolites' response to high temperature. Our study will contribute to the identification of heat tolerance genes in maize, therefore contributing to the breeding of heat-tolerant maize varieties.